For many decades now, many different forms or styles of blind fasteners have been provided for engagement with many different types of work pieces. Such fasteners are used in extremely large quantities on trucks and trailers and on metal buildings and the like, and permit the installer to effect a strong, effective engagement between such fastener and a work piece, with installation being from only a single side.
Typically, such blind fasteners employ a hollow tubular member wherein a mandrel is slideably positioned, the blind end portions of each of such members being connected together so that pulling on the mandrel causes collapse of the hollow tubular member.
Prior devices have shown some inconsistencies with respect to effective installation, due to the dimensional and metallurgical inconsistencies of each tubular rivet body. That is, it is not uncommon in such blind fasteners for the rivet body to be stronger on one side than the other due to differences in mettalurgical content or wall thickness, or the like. As a result, such prior structures have been subject to tilting and turning as the mandrel or stem is pulled by the automatic installation tool for the purpose of collapsing the tubular member against the work piece. As such, it has long been a desired objective to provide a blind fastener wherein the tubular rivet is caused to collapse uniformly on all sides so as to engage the work piece uniformly thereabout, and to apply a uniform pressure on the blind side of the work piece even when the holes in the work pieces are considerably larger than the body of the fastener and are misaligned.